Diameter Signaling Router (DSR) - Transmission Control Protocol (TCP) Responder Connections Were Down

Asset ID:	1-71-2352986.1
Update Date:	2018-01-29
Keywords:

Solution Type Technical Instruction Sure

Solution 2352986.1 : Diameter Signaling Router (DSR) - Transmission Control Protocol (TCP) Responder Connections Were Down

Applies to:

Oracle Communications Diameter Signaling Router (DSR) - Version DSR 7.1.0 and later
Tekelec

Goal

After customer's maintenance windows for changing a UTP cable for a fiber network, they started getting following alarms on the Active SOAM (System Operation And Maintenance) indicating connections down towards peer node :

Solution

On investigating we found that the down connections towards peer node were TCP Responder type connection

Since the connection mode is Responder only and Operational reason is Listening, this means that DSR is waiting for connection establishment message (SYN),from Peer node. Verify if the connection establishment messages are reaching DSR using below tshark command

tshark -i any -f "host <primary peerIP> and host <primary dsrIP>"

Peer node was requested to start the connection from their end. Once this was done the connections came up normally and the Critical alarm (22051) and Major alarm (22101) got cleared.

Below is the diagram which explains the TCP 3 way handshake procedure for Connection Establishment at Transport layer :

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